Background
: SARS-CoV-2 quickly spreads in the worldwide population, imposing social restrictions to control the infection, being the massive testing another essential strategy to break the chain of transmission.
Aim
: To compare the performance of at-home self-collected samples – saliva and combined nasal-oropharyngeal swabs (NOP) – for SARS-CoV-2 detection in a telemedicine platform for COVID-19 surveillance.
Material and methods
: We analyzed 201 patients who met the criteria of suspected COVID-19. NOP sampling was combined (nostrils and oropharynx) and saliva collected using a cotton pad device. Detection of SARS-COV-2 was performed by using the Altona RealStar® SARS-CoV-2 RT-PCR Kit 1.0.
Results: There was an overall significant agreement (κ coefficient value of 0.58) between saliva and NOP. Considering results in either sample, 70 patients positive for SARS-CoV-2 were identified, with 52/70 being positive in NOP and 55/70 in saliva. This corresponds to sensitivities of 74.2% (95% CI; 63.7% to 83.1%) for NOP and 78.6% (95% CI; 67.6% to 86.6%) for saliva.
Conclusion
: Our data show the feasibility of using at-home self-collected samples (especially saliva), as an adequate alternative for SARS-CoV-2 detection. This new approach of testing can be useful to develop strategies for COVID-19 surveillance and for guiding public health decisions.
A B S T R A C TObjectives: This study was performed to determine whether neutralizing antibodies against yellow fever virus (YFV) generated by YFV vaccine could interfere in the specificity of dengue virus (DENV) and Zika virus (ZIKV) IgG ELISA tests. Methods: Seventy-nine pairs of serum samples (pre-and post-vaccination), collected during the years 1997-1998 from children with no history of yellow fever disease who had been vaccinated against YFV, were tested. The seroconversion post-vaccination was evaluated through plaque reduction neutralization test (PRNT), and four different commercial ELISA kits were used for the detection of DENV and ZIKV IgG antibodies. Results: A cross-reactivity rate of 3.9% with DENV IgG antibodies was found only with the Dengue Virus IgG Dx Select kit (Focus Diagnostics). Conclusions: As several countries have local transmission of multiple arboviruses, the absence of crossreactivity or minimum cross-reactivity of YFV neutralizing antibodies with DENV and ZIKV antigens is a relevant finding, since the interpretation of sero-epidemiological investigations would be seriously impacted in many regions where YFV vaccination is mandatory.
Zika virus (ZIKV) clinical presentation and frequency/duration of shedding need
further clarification. Symptomatic ZIKV-infected individuals identified in two
hospitals in Sao Paulo State, Brazil, were investigated regarding clinical
characteristics, shedding in body fluids, and serodynamics. Ninety-four of 235
symptomatic patients (Site A: 58%; Site B: 16%) had Real-Time PCR-confirmed ZIKV
infection; fever, headache and gastrointestinal symptoms were less frequent, and
rash was more frequent compared to ZIKV-negative patients. Real-Time PCR in
serum had worse performance compared to plasma, while urine had the highest
sensitivity. Shedding in genital fluids and saliva was rare. IgM positivity was
the highest <14 days after the symptoms onset (86%), decreasing >28 days
(24%); IgG positivity increased >14 days (96%) remaining positive in 94% of
patients >28 days. ZIKV prevalence varied importantly in two neighboring
cities during the same transmission season. Urine Real-Time PCR can improve
diagnostic sensitivity; serum testing is less useful. Accurate serological tests
are needed to improve diagnosis and surveillance.
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